Femtosecond UV studies of the electronic relaxation processes in Cytochrome c

We report on an experimental study with UV and visible ultrafast time-gated emission and transient absorption of the early photodynamics of horse heart Cytochrome c in both ferric and ferrous redox states. A clear separation in time and energy of tryptophan and haem emission is observed. Excitation...

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Bibliographic Details
Published in:The journal of physical chemistry. B Vol. 115; no. 46; p. 13723
Main Authors: Bräm, Olivier, Consani, Cristina, Cannizzo, Andrea, Chergui, Majed
Format: Journal Article
Language:English
Published: United States 24.11.2011
Subjects:
Animals
Cytochromes c - chemistry
Electrons
Energy Transfer
Heme - chemistry
Horses
Oxidation-Reduction
Spectrophotometry, Ultraviolet
Time Factors
Tryptophan - chemistry
ISSN:1520-5207, 1520-5207
Online Access:Get more information
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Summary:We report on an experimental study with UV and visible ultrafast time-gated emission and transient absorption of the early photodynamics of horse heart Cytochrome c in both ferric and ferrous redox states. A clear separation in time and energy of tryptophan and haem emission is observed. Excitation of the haem via resonant energy transfer from the tryptophan residue is observed in the subsequent haem electronic relaxation. Different Trp-haem energy transfer time constants of the ferrous and ferric forms are obtained. An almost instantaneous relaxation to the lowest singlet excited state (corresponding to the so-called Q band) characterizes the earliest electronic dynamics of the haem, independent of excitation energy, while dark intermediate states govern the ground-state recovery. The information gathered in these two experiments and in the literature allows us to propose a simple scheme for the electronic relaxation leading to ligand dissociation.
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ISSN:1520-5207
1520-5207
DOI:10.1021/jp207615u